This invention relates to heating catheters, and especially to balloon catheters and similar devices used to apply heat within a patient's body, for hyperthermic treatment of tumors and other medical procedures.
Certain lesions, such as tumors or plaque deposits located in or near various ducts of the body, are positioned eccentrically, rather than concentrically, with respect to the duct. For example, a tumor of the esophagus might be located eccentrically on one side of the esophagus. Such a tumor might typically be treated by inserting a balloon catheter into the esophagus and heating fluid inside the balloon.
The extent of heating of tissue is a function of the amount of compression of the tissue. As tissue is compressed, it loses its ability to act as a heat sink, and hence the temperature of the compressed tissue increases. The amount of compression of the tissue is dependent upon the volume occupied by the balloon relative to the diameter of the vessel or duct. The compression of the tissue is not necessarily dependent upon the pressure inside the balloon, however, because the pressure inside the balloon is a consequence of the resistance of the balloon itself to expansion, especially if the balloon is nondistensible, rather than a consequence of the resistance of the tissue to expansion of the balloon.